The new data suggests that omega-3 fatty acids and their metabolite products slow or stop the proliferation (or growth) of cancer cells, but are especially effective at blocking the growth of triple-negative breast cancer cells.
Led by Thomas Pogash from Fox Chase Cancer Center, USA, the team found that the omega-3s worked against all types of cancerous cells, but the effect was observed to be stronger in triple-negative cell lines – where it reduced proliferation by as much as 90%.
Pogash said the findings underscores the important role common compounds found in food may play in keeping cancer at bay: "Diet can play a critical role in breast cancer prevention,” he said.
"When you compare a western diet to a mediterranean diet, which has more omega-3s, you see less cancer in the mediterranean diet. They eat much more fish."
The research findings, presented at the AACR Annual Meeting 2013, assessed omega-3 fatty acids ability to inhibit the growth of the four lines of breast cancer cells that are generally recognised.
Two of those, luminal A and luminal B, grow in the luminal cells that line milk ducts in the breast and have receptors for oestrogen and progesterone, while a third category includes tumours that test positive for the HER2 receptor.
Tumors in the fourth category, triple-negative, lack receptors for progesterone, estrogen, and a protein called HER2/neu - as a result, this type of disease is insensitive to some cancer treatments like trastuzumab, which disrupts the HER2 receptor, and tamoxifen, which targets the estrogen receptor.
The authors noted that no targeted therapies are currently available for patients diagnosed with triple-negative breast cancer:
"This type of cancer, which is found more frequently in Latina and African-American women, is highly aggressive and has a low survival rate," said Dr Jose Russo – who also worked on the study. "There is not any specific treatment for it."
Russo, Pogash, and their colleagues tested the effect of large omega-3 parent molecules, as well as their smaller metabolic derivatives, on three luminal cell lines and seven lines that included basal-type triple-negative cells.
They found that omega-3 and its metabolites inhibited proliferation in all cell lines, but the effect was dramatically more pronounced in the triple-negative cell lines.
In addition, the metabolites of omega-3 reduced motility by between 20% and 60% in the triple-negative basal cell lines, they said.